U.S. patent number 7,692,904 [Application Number 11/901,759] was granted by the patent office on 2010-04-06 for ground fault circuit interrupter.
Invention is credited to Xiaobing Dong, Xuguang Li, Yi Yin.
United States Patent |
7,692,904 |
Li , et al. |
April 6, 2010 |
Ground fault circuit interrupter
Abstract
A method of preventing an overload current from a power supply
to a load through a ground fault circuit interrupter includes the
steps of: obtaining an interrupted fault current from a hot wire to
a ground wire via a first zero-phase current inductor and a fault
current from a neutral wire to the ground wire via a second
zero-phase current inductor; amplifying a signal of the fault
current by an Op-Amp; and determining the fault current by a
programmable control module, wherein when the fault current is
larger than a preset threshold, the programmable control module
sends a control signal to a control switch such that the control
switch electrifies a second coil of a trip breaker to drive an
armature at an unlocked position, so as to separate a movable
terminal with a fixed terminal for electrically disconnecting the
load with the power supply.
Inventors: |
Li; Xuguang (Yantian Village,
Fenggang Town, Dongguan City, Guangdong ProvincN/A, CN),
Dong; Xiaobing (Yantian Village, Fenggang Town, Dongguan City,
Guangdong ProvincN/A, CN), Yin; Yi (Yantian Village,
Fenggang Town, Dongguan City, Guangdong ProvincN/A, CN) |
Family
ID: |
39762428 |
Appl.
No.: |
11/901,759 |
Filed: |
September 18, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080225448 A1 |
Sep 18, 2008 |
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Current U.S.
Class: |
361/45;
361/42 |
Current CPC
Class: |
H02H
11/002 (20130101) |
Current International
Class: |
H02H
3/00 (20060101) |
Field of
Search: |
;361/42-50,71-74 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Nguyen; Danny
Attorney, Agent or Firm: Chan; Raymond Y. David and Raymond
Patent Firm
Claims
What is claimed is:
1. A ground fault circuit interrupter for preventing an overload
current from a power supply to a load, comprising: a first module
supplying a unipolar .ident.power supply; a second module obtaining
a fault current in responsive to a hot wire and a neutral wire with
a ground wire; a third module amplifying a signal of said fault
current from said second module; a fourth module which comprises a
programmable control module for determining said fault current,
wherein when said programmable control module presets a preset
threshold for said fault current to be compared; a fifth module
comprising an End-of-life circuitry performing an automatic
self-checking operation; a sixth module which comprises a control
switch, a trip breaker, an armature, a locking device, a movable
terminal, and a fixed terminal, wherein when said fault current is
larger than said preset threshold, said programmable control module
sends a control signal to said control switch such that said
control switch electrifies a second coil of said trip breaker to
drive an armature to actuate said locking device, so as to move
said movable terminal away from said fixed terminal for
electrically disconnecting said load with said power supply; and a
seventh module comprising a reset circuitry for resetting said trip
breaker and a test circuitry for checking a status of said trip
breaker.
2. The ground fault circuit interrupter, as recited in claim 1,
wherein said test circuitry of said seventh module comprises a LED
indicator producing an illuminating signal to indicate said status
of said ground fault circuit interrupter, wherein when said fault
current is not larger than said preset threshold that said ground
fault circuit interrupter is normally operated, a slow-twinkling
signal is generated, and when said fault current is larger than
said preset threshold that said ground fault circuit interrupter is
abnormally operated, a fast-twinkling signal is generated.
3. The ground fault circuit interrupter, as recited in claim 1,
wherein said fifth module comprises a transient voltage suppressor
electrically coupling with said control switch, wherein when said
wires are misconnected, said control switch and said transient
voltage suppressor are connected between said neutral wire and said
ground wire in series connection such that an electric potential
between said neutral wire and said ground wire is relatively high
to conduct said transient voltage suppressor, wherein said control
switch is then electrified to separate said movable terminal with
said fixed terminal for electrically disconnecting said load with
said power supply so as to prohibit said ground fault circuit
interrupter from being reset to re-connect said load with said
power supply unless said hot wire and said neutral wire are
connected properly.
4. The ground fault circuit interrupter, as recited in claim 2,
wherein said fifth module comprises a transient voltage suppressor
electrically coupling with said control switch, wherein when said
wires are misconnected, said control switch and said transient
voltage suppressor are connected between said neutral wire and said
ground wire in series connection such that an electric potential
between said neutral wire and said ground wire is relatively high
to conduct said transient voltage suppressor, wherein said control
switch is then electrified to separate said movable terminal with
said fixed terminal for electrically disconnecting said load with
said power supply so as to prohibit said ground fault circuit
interrupter from being reset to re-connect said load with said
power supply unless said hot wire and said neutral wire are
connected properly.
5. The ground fault circuit interrupter, as recited in claim 1,
wherein a first coil of said trip breaker is not electrified to
drive said armature to actuate said locking device when said
neutral wire and said hot wire are reversely connected, so as to
prohibit said ground fault circuit interrupter from being reset to
re-connect said load with said power supply unless said hot wire
and said neutral wire are connected properly.
6. The ground fault circuit interrupter as recited in claim 4,
wherein a first coil of said trip breaker is not electrified to
drive said armature to actuate said locking device when said
neutral wire and said hot wire are reversely connected, so as to
prohibit said ground fault circuit interrupter from being reset to
re-connect said load with said power supply unless said hot wire
and said neutral wire are connected properly.
7. The ground fault circuit interrupter, as recited in claim 1,
wherein said second module comprises two zero-phase current
inductors for obtaining said fault current from said hot wire to
said ground wire and from said neutral wire to said ground wire,
wherein one of said current inductors has a coil ratio of primary
and secondary windings being set as 1:1000 while another said
current inductor has a coil ratio of primary and secondary windings
being set as 1:200.
8. The ground fault circuit interrupter, as recited in claim 6,
wherein said second module comprises two zero-phase current
inductors for obtaining said fault current from said hot wire to
said ground wire and from said neutral wire to said ground wire,
wherein one of said current inductors has a coil ratio of primary
and secondary windings being set as 1:1000 while another said
current inductor has a coil ratio of primary and secondary windings
being set as 1:200.
9. A method of preventing an overload current from a power supply
to a load through a ground fault circuit interrupter, comprising
the steps of: (a) obtaining an interrupted fault current from a hot
wire to a ground wire via a first zero-phase current inductor and a
fault current from a neutral wire to the ground wire via a second
zero-phase current inductor; (b) amplifying a signal of said fault
current by an Op-Amp; and (c) determining said fault current by a
programmable control module, wherein when said fault current is
larger than a preset threshold, said programmable control module
sends a control signal to a control switch such that said control
switch electrifies a second coil of a trip breaker to drive an
armature at an unlocked position, so as to separate a movable
terminal with a fixed terminal for electrically disconnecting said
load with said power supply; (d) determining said hot wire and said
neutral wire are connected improperly by determining whether said
hot-wire and said neutral wire are reversely connected, wherein
when said hot wire and said neutral wire are reversely connected, a
first coil of said trip breaker is not electrified to actuate said
armature; and (e) prohibiting said ground fault circuit interrupter
from being reset to re-connect said load with said power supply
unless said hot wire and said neutral wire are connected
properly.
10. The method, as recited in claim 9, wherein said step (e)
comprises a step of keeping said movable terminal away from said
fixed terminal to prohibit a re-connection between said load and
said power supply when said ground fault circuit interrupter is
reset.
11. A method of preventing an overload current from a power supply
to a load through a ground fault circuit interrupter, comprising
the steps of: (1) obtaining an interrupted fault current from a hot
wire to a ground wire via a first zero-phase current inductor and a
fault current from a neutral wire to the ground wire via a second
zero-phase current inductor; (2) amplifying a signal of said fault
current by an Op-Amp; (3) determining said fault current by a
programmable control module, wherein when said fault current is
larger than a preset threshold, said programmable control module
sends a control signal to a control switch such that said control
switch electrifies a second coil of a trip breaker to drive an
armature at an unlocked position, so as to separate a movable
terminal with a fixed terminal for electrically disconnecting said
load with said power supply; (4) performing an automatic
self-checking operation to determine a status of said ground fault
circuit interrupter in responsive to said fault current whether in
a normal operation; and (5) producing an illuminating signal to
indicate said status of said ground fault circuit interrupter in
condition that: when said fault current is not larger than said
preset threshold that said ground fault circuit interrupter is
normally operated, a slow-twinkling signal is generated; and when
said fault current is larger than said preset threshold that said
ground fault circuit interrupter is abnormally operated, a
fast-twinkling signal is generated.
12. The method, as recited in claim 11, further comprising the step
(3.1), in between said step (3) and said step (4), of determining
said hot wire and said neutral wire are connected improperly; and
step (3.2) of prohibiting said ground fault circuit interrupter
from being reset to re-connect said load with said power supply
unless said hot wire and said neutral wire are connected
properly.
13. The method, as recited in claim 12, wherein the step (3.1)
further comprises the steps of: (3.1.1) obtaining a magnitude of
said fault current will flowing through said neutral wire, wherein
said hot wire and said neutral wire are electrically misconnected
when said magnitude of said fault current is relatively high; and
(3.1.2) electrifying said control switch to separate said movable
terminal with said fixed terminal for electrically disconnecting
said load with said power supply.
14. The method, as recited in claim 12, wherein said step (3.1)
further comprises a step of determining whether said hot wire and
said neutral wire are reversely connected, wherein when said hot
wire and said neutral wire are reversely connected, a first coil of
said trip breaker is not electrified to actuate said armature.
15. The method, as recited in claim 13, wherein said step (3.2)
comprises a step of keeping said movable terminal away from said
fixed terminal to prohibit a re-connection between said load and
said power supply when said ground fault circuit interrupter is
reset.
16. The method, as recited in claim 14, wherein said step (3.2)
comprises a step of keeping said movable terminal away from said
fixed terminal to prohibit a re-connection between said load and
said power supply when said ground fault circuit interrupter is
reset.
Description
BACKGROUND OF THE PRESENT INVENTION
1. Field of Invention
The present invention relates to a ground fault circuit
interrupter, and more particularly to an always-open trip breaker
used in a ground fault circuit interrupter with a programmable
integrated module and an End-of-life termination function.
2. Description of Related Arts
When the hot wire or neutral wire is short circuited to the ground,
the ground fault circuit interrupter is used as an electrical
switch not only for protecting the electrical circuit of the
electrical appliance from being damaged caused by overload or short
circuiting but also for preventing the user from being electric
shocked. The ground fault circuit interrupter has a higher
sensitivity and faster response in comparison with other protection
devices, such as fuse or automatic switch. The ground fault circuit
interrupter can rapidly cut off the current and prevent current
overload.
Accordingly, the automatic switch or the fuse has an operation
value corresponding to the normal operation current in order to
withstand the operation current passing through. Once the fault
current is larger than the operation value, the automatic switch or
the fuse will cut off the electrical connection between the load
and the power supply. On the other hand, the leakage protector use
the residual current produced in the ground fault to cut off the
power supply. Therefore, the operation value of the leakage
protector is relatively small (generally set as 6 milliampere).
However, when the current is leaked by human contact or to the
outer casing, the residual current will substantially increase. It
is worth mentioning that the ground fault circuit interrupter can
determine and stop the residual current so as to cut off the
current from the power supply.
Generally speaking, the ground fault circuit interrupter comprises
a trigging mechanism to rapidly cut off the current to the
electrical appliance, wherein there are two different types of
tripping mechanisms being commonly used. The first type is the
"always-close" type tripping mechanism electrically connecting to
the movable terminal and the fixed terminal for electrical
connection. The mechanical pressure between the movable terminal
and the fixed terminal relies on the trip breaker of the tripping
mechanism implemented using a solenoid or electromagnet force. The
advantage of such "always-close" tripping mechanism is that the
operation is reliable, the circuit and the mechanism is simple.
However, the drawback of such "always-close" type tripping
mechanism is that the coil of the trip breaker consumes part of the
electrical power. Another type is the "always-open" type tripping
mechanism relying on an impulsive current to the coil of the trip
breaker such that the trip breaker shifts at an off-balance state
by means of the electromagnetic force to electrically connect with
the movable terminal and the fixed terminal. Accordingly, a locker
is incorporated with the trip breaker to provide a mechanical
pressure between the movable terminal and the fixed terminal. Such
"always-open" tripping mechanism requires the locker and a logic
circuit to incorporate with the trip breaker, such that the
"always-open" tripping mechanism has relatively complicated
electrical and mechanical configurations. However, the
"always-open" tripping mechanism does not require any current
passing through the coil thereof for operation. In other words, the
"always-open" tripping mechanism does not normally consume any
electrical power. Comparing with the two different types of
tripping mechanisms, the "always-close" tripping mechanism is
commonly used for the simple IC circuit product because the
"always-close" tripping mechanism has simplified electrical and
mechanical configurations.
The ground fault circuit interrupter generally comprises a fault
current induction mechanism, including a sensor coil and a driver
coil, a signal rectifying circuit, a signal amplifying circuit, a
signal comparing circuit, a threshold switch circuit, an operation
mechanism, and other peripheral circuits. Accordingly, a signal
induction mechanism comprises two zero-phase current inductors,
wherein one of the current inductors has a coil ratio of primary
and secondary windings being set as 1:1000 while another current
inductor has a coil ratio of primary and secondary windings being
set as 1:200. The signal rectifying circuit is coupled with
capacitors and resistors to form a signal extraction circuit,
wherein the signal amplifying circuit and the signal comparing
circuit are combined to form a semiconductor chip such as LM1851
chip from National and RV4145A chip from Fairchild. The threshold
switch circuit comprises a silicon controlled rectifier (SCR). The
operation mechanism comprises a trip breaker and its corresponding
components thereof, and peripheral circuit and components
comprising a movable terminal, a fixed terminal, a test button, and
a reset button. Before the standard of UL943-2006 is set, the
function of the ground fault circuit interrupter is that: (1) when
the hot wire and neutral wire is faulty to the ground, and the
fault current is bigger than 6 mA, the power supply is cut off; (2)
when there is no fault current or the fault current is not larger
than the threshold, the ground fault circuit interrupter can be
reset by the reset button to re-connect the ground fault circuit
interrupter with the power supply; (3) the test button is used for
testing the function of the ground fault circuit interrupter by
pressing the test button to cut off the power supply; (4) when the
wires at the load and the power supply are reversely connected, the
ground fault circuit interrupter cannot be electrified so as to
protect the load in responsive to the improper connection.
According to the standard before UL943-2006, the ground fault
circuit interrupter does not have the End-of-life automatic
self-checking function. The user manually presses the test button
to check whether the ground fault circuit interrupter is faulty or
failed. The trip breaker must be operated with the constant power
supply, which will shorten the service life of the trip breaker.
Thus, there is no indicating signal, such as sound signal or light
signal, to indicate the operating status of the trip breaker.
Along with the programmable integrated module application, it is
possible to incorporate the programmable integrated module with the
"always-open" tripping mechanism with the logical control.
The present invention provides a programmable integrated module and
a control switch incorporating with the "always-open" tripping
mechanism to cut off the current exceeding the breaker rating and
to protect the wrong wiring connection of the circuit.
SUMMARY OF THE PRESENT INVENTION
A main object of the present invention is to provide a ground fault
circuit interrupter that meets the requirement of the UL-943-2006,
wherein the trip breaker is arranged to cut off the electric
connection between the power supply and the load when the fault
current is larger than the preset value. In addition, the trip
breaker of the present invention also cuts off the electrical
connection between the power supply and the load when the wires are
misconnected or improperly connected. Thus, the trip breaker does
not consume any power during normal operation.
Another main object of the present invention is to provide a ground
fault circuit interrupter with a programmable integrated module,
which is capable of performing an End-of-life automatic
self-checking, that satisfies the UL943-2006. In addition, the
ground fault circuit interrupter is adapted for indicating the
working status of the ground fault circuit interrupter by twinkling
frequency of the LED indicator. When the ground fault circuit
interrupter is normally operated, the LED indicator generates a
slow-twinkling light signal with the frequency of 0.1 Hz. When the
ground fault circuit interrupter is abnormally operated, including
the signal induction mechanism or the operation mechanism being
malfunction, the LED indicator generates a fast-twinkling light
signal with the frequency of 1 Hz to indicate the service life of
the ground fault circuit interrupter is terminated.
Another object of the present invention is to provide a ground
fault circuit interrupter, wherein when the wires at the load and
the power supply (or power line) are reversely connected, the
programmable integrated module and the control switch cannot be
electrified, such that the trip breaker cannot be operated to
re-connect the load with the power supply through the reset
button.
Another object of the present invention is to provide a ground
fault circuit interrupter, wherein when the hot wire and the
neutral wire are misconnected, the programmable integrated module
will perform the self-checking operation by pressing the reset
button. When the driver coil obtains a fault current larger than 6
mA, through the electromagnetically coupling with the sensor coil,
the programmable integrated module will obtain a current signal
which is larger than 6 mA. Then, the programmable integrated module
will send a trigger signal to the gate electrode of the SCR to
electrify the coil of the trip breaker and drive the armature to
move. Therefore, the locking device is driven to move by the
armature to move the movable terminal away from the fixed terminal
by means of resilient spring force so as to cut off the electrical
connection between the load and the power supply. Accordingly, the
trip breaker cannot be reset by the reset button to re-connect the
load with the power supply unless the wires are electrically
connected in a proper manner.
Another object of the present invention is to provide a ground
fault circuit interrupter, wherein the two coils are kept in
"always-open" condition by the programmable integrated module such
that the trip breaker is controllably operated by the determination
of the output terminal of the sensor coil. In other words, the trip
breaker is actuated to cut off the electrical connection when the
sensor coils inducts the fault current larger than 6 mA. Otherwise,
the trip breaker is not being electrified during normal
operation.
Accordingly, in order to accomplish the above object, the present
invention provides a method of preventing an overload current
through a ground fault circuit interrupter, comprising the steps
of: obtaining an interrupted fault current from a hot wire to a
ground wire via a first zero-phase current inductor and a fault
current from a neutral wire to the ground wire via a second
zero-phase current inductor; amplifying a signal of the fault
current by an Op-Amp; and determining the fault current by a
programmable control module, wherein when the fault current is
larger than a preset threshold, the programmable control module
sends a control signal to a control switch such that the control
switch electrifies a second coil of the trip breaker to drive an
armature at an unlocked position, so as to separate the movable
terminal with the fixed terminal by a resilient spring force for
electrically disconnecting the load with the power supply. At the
same time, the programmable control module periodically sends out
an adjustment signal to a terminal of the control switch in which
the terminal thereof is connected between the neutral wire and the
ground wire, so as to conduct the control switch periodically.
Therefore, the programmable control module ensures a resistor
between the neutral wire and the ground wire of the load being set
at 1 ohm via hardware so as to satisfy the standard of the
UL-943-2006. The driver coil is adapted to produce an instant
short-circuit current, wherein an induced current signal is
generated by electromagnetic coupling the driver coil with the
sensor coil. Through the Op-Amp and the programmable control
module, the fault current is determined in order to compare with
the preset threshold. When the value of the fault current equals to
the preset threshold, the programmable control module will sends a
slow-twinkling signal to a LED as an End-of-life sign to indicate
the system is normally operated. On the other hand, when the system
is failed to operate, the programmable control module will send a
fast-twinkling signal to the LED to perform the End-of-life of
UL-943-2006 of the automatic self-checking function through the
hardware and software. By obtaining the current and incorporating
with the trip breaker, the electrical connection between the load
and the power supply is cut off to provide a safety feature of the
load and to prevent the user being electric shock. The programmable
control module is the core of the system of the present invention,
wherein the circuit configuration is simple and is in low cost, and
satisfies the relevant requirement of UL-943-2006. The trip
breaker, which has a simple structural configuration and a smaller
size, comprises the control switch, operating coils, an armature, a
supporting frame, and a contact. Thus, the trip breaker, which is
the "always-open" type tripping mechanism", is adapted to reduce
the power consumption of the working coils during operation so as
to prolong the service life of the working coils.
Accordingly, the trip breaker comprises two coils, a programmable
control module having gate levels of input/output ports connecting
to the coils respectively to operate a connection between a movable
terminal and a fixed terminal. To meet the requirements of
UL-943-2006 and other relevant standards, the electrical connection
and the load is cut off when the fault current is larger than the
preset threshold and when the wires are misconnected or improperly
connected. Since the two coils are always in an "always-open"
condition, the coils do not consume any energy during the normal
operation of the ground fault current interrupter.
The programmable control module of the present invention is adapted
to cut off the fault current, including the hot wire ground fault
and the neutral wire ground fault, when the fault current is larger
than the preset threshold. Accordingly, the programmable integrated
module, the control switch, and the trip breaker with the locking
device form the "always-open" type tripping structure.
The present invention prohibits the re-connection between the load
and the power supply even though the reset button of the system is
actuated. When the wires are misconnected, the control switch,
which is positioned between neutral wire and the ground wire for
use in the End-of-life self checking operation, is electrically
connected in parallel with a transient voltage suppressor to
protect the control switch. At the same time, the driver coil will
produce the induced current signal by electromagnetic coupling the
driver coil with the sensor coil through the transient voltage
suppressor to let the programmable control module for
determination. By setting the gate level of the coil 1 of the trip
breaker, which is electrically connected to the control switch, in
a relatively high level, the second coil of the trip breaker is
electrified to actuate the armature to operate the locking device.
When the locking device is unlocked to separate the movable
terminal from the fixed terminal, the electrical connection between
the load and the power supply is cut off.
The present invention also prohibits the re-connection between the
load and the power supply even though the reset button of the
system is actuated. When the wires are improperly connected, such
as the wires are connecting reversely, the circuit configuration of
the present invention ensures the programmable integrated module
and the control switch not being electrified.
The present invention also prohibits the re-connection between the
load and the power supply even though the reset button of the
system is actuated. When the wires are misconnected, the
programmable integrated module logically determines the
misconnection of the wires and sets the first coil of the trip
breaker at a low electrical level to form an open circuit of the
first coil. Therefore, the armature cannot be electrified to
actuate for unlocking the locking device. Due to the spring force,
the movable terminal and the fixed terminal cannot be contacted so
as to prohibit the electrical connection.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a ground fault circuit interrupter
according to a preferred embodiment of the present invention.
FIG. 2 is the schematic view of a trip breaker of the ground fault
circuit interrupter according to the above preferred embodiment of
the present invention.
FIGS. 3A and 3B illustrate the trip breaker cutting off the
electrical connection between the load and the power supply when
hot wire is short to the ground and the fault current exceeds
preset threshold.
FIGS. 4A and 4B illustrate the trip breaker cutting off the
electrical connection between the load and the power supply when
neutral wire is short to the ground and the fault current exceeds
preset threshold.
FIGS. 5A and 5B illustrate the trip breaker prohibiting the
electrical connection between the load and the power supply when
the wires are misconnected.
FIG. 6 illustrates the trip breaker prohibiting the electrical
connection between the load and the power supply when the wires are
reversely connected.
FIG. 7 is a block diagram illustrating the structural configuration
of a ground fault circuit interrupter according to the above
preferred embodiment of the present invention.
FIG. 8 is a circuit diagram illustrating the electrical
configuration of the programmable integrated module according to
the above preferred embodiment of the present invention.
FIG. 9 is a circuit diagram illustrating the electrical
configuration of the ground fault circuit interrupter according to
the above preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1 of the drawings, a ground fault circuit
interrupter according to a preferred embodiment of the present
invention is illustrated, wherein the ground fault circuit
interrupter is constructed by seven functional modules.
Accordingly, the ground fault circuit interrupter comprises a first
module 1 as a power supply module, third and fourth modules 3, 4
being electrically coupling with the first module 1 that the first
module 1 supplies a unipolar +5V power supply to the third and
fourth modules 3, 4. A second module 2 as an induction sensor and a
signal adjusting circuitry is arranged to obtain a ground fault
current and an End-of-life self-checking current through a sensor
coil and a driver coil. The third module 3 as a signal amplifying
circuit amplifies a current from the second module 2 to the fourth
module 4 for determining a working status of the ground fault
circuit interrupter. The fourth module 4 as a programmable
integrated module is arranged for determining the magnitude of the
ground fault current, for determining an automatic End-of-life
self-check, and for generating a trigger signal for further
mechanical operation and the operation of LED indicator. Therefore,
the fault current and the misconnected wires can be determined and
the automatic End-of-life self-check can be performed. A fifth
module 5 is a circuit of the automatic End-of-life self-check to
periodically ground a preset neutral wire with a fixed resistor
through the second module 2, the third module 3, the fourth module
4, and the LED indicator. A sixth module 6 is an operation unit of
the fault circuit interrupter for moving the movable terminal 201
away from the fixed terminal 202 when the fault current exceeds the
preset threshold, so as to cut off the electrical connection
between the load and the power supply. Thus, the sixth module 6
prohibits the re-connection between the load and the power supply
when the wires are misconnected or improperly connected even though
the reset button 301 of the system is actuated. A seventh module 7
comprises a trip breaking mechanism and an accessory mechanism
which comprises the movable terminal 201, the fixed terminal 202,
the LED indicator for indicating the operating status of the ground
fault circuit interrupter, the reset button 301, and a test button
302 for cooperating with other modules of the ground fault circuit
interrupter.
As shown in FIG. 2, the ground fault circuit interrupter comprises
two trip coils 1, 2, a supporting frame 204, a locking device 203,
the movable terminal 201, the fixed terminal 202, an armature 100,
the reset button 301, and the test button 302.
FIG. 3 illustrates the operation of the trip breaker cutting off
the electrical connection between the power supply and the load, as
the hot wire is short to the ground. As the fault current occurs
between the hot wire and the ground, the driver coil of the first
module 1 inducts the fault current as an induction current and
incorporates with a capacitor 1 having a potential difference to
form a signal extraction circuit. Accordingly, the induction
current is amplified by the third module 3 and is sent to the first
I/O port of the fourth module 4. The fourth module 4 will compare
the electric potential at the first I/O port with a preset value.
If the electric potential at the first I/O port is larger than the
preset value, the fourth module 4 will set the gate of a first
switch at a relative high level through a second I/O port. Once the
control switch is activated, the second coil of the trip breaker is
electrified to drive the armature 100 by electromagnetic force to
move. Accordingly, the armature 100 moves from the first position,
as shown in FIG. 3A, to the second position as shown in FIG. 3B.
Correspondingly, the locking device 203 moves from the first
position as shown in FIG. 3A to the second position as shown in
FIG. 3B. The movable terminal 201 1 is in contact with the fixed
terminal 202 as shown in FIG. 3A and is driven to move away from
the fixed terminal 202 through the supporting frame 204 as shown in
FIG. 3B. The electrical connection between the power supply and the
load is cut off once the movable terminal 201 is moved away from
the fixed terminal 202 under a fault circuit condition.
FIG. 4 illustrates the operation of the trip breaker cutting off
the electrical connection between the power supply and the load, as
the neutral wire is short circuit to the ground and the fault
current exceeds the preset threshold. As the fault current occurs
between the neutral wire at the load side and the ground, the
driver coil of the first module 1 inducts the fault current as an
induction current and superposes a fault current on a full-wave
rectified signal by electromagnetic induction. In other words, the
fault current passes through the driver coil of the first module 1
to obtain an induction current by electromagnetic induction. By
incorporating with a capacitor 1 having a potential difference, a
signal extraction circuit is formed. The induction current is
amplified by the third module 3 and is sent to the first I/O port
of the fourth module 4. The fourth module 4 will compare the
electric potential at the first I/O port with a preset value. If
the electric potential at the first I/O port is larger than the
preset value, the fourth module 4 will set the gate of a first
switch at a relative high level through a second I/O port. Once the
two-way control switch is conducted to electrify the second coil of
the trip breaker, the second coil will drive the armature 100 by
electromagnetic force to actuate the locking device 203.
Accordingly, the armature 100 moves from a first position as shown
in FIG. 4A to a second position as shown in FIG. 4B.
Correspondingly, the locking device 203 moves from a first position
as shown in FIG. 4A to a second position as shown in FIG. 4B. The
movable terminal 201 1 is in contact with the fixed terminal 202 as
shown in FIG. 4A and is driven to move away from the fixed terminal
202 through the supporting frame 204 as shown in FIG. 4B. The
electrical connection between the power supply and the load is cut
off once the movable terminal 201 is moved away from the fixed
terminal 202 under a fault circuit condition.
FIG. 5 illustrates the operation of the trip breaker prohibiting
the re-connection between the load and the power supply even though
resetting the trip breaker by the reset button 301, as the wires
are misconnected, i.e. the hot wire is connected with the neutral
wire. When the wires are misconnected, a two-way control switch
tube and a transient voltage suppressor are connected between the
neutral wire and ground wire in series connection. Accordingly, the
electric potential between the neutral wire and the ground wire is
relatively high to conduct the transient voltage suppressor,
wherein a relatively high magnitude of fault current will flows
through the neutral wire. Then, when the fault current passes
through the driver coil, the driver coil inducts the sensor coil by
electromagnetic force to obtain an induction current. By
incorporating with a capacitor 1 having a potential difference, a
signal extraction circuit is formed. The induction current is
amplified by the third module 3 and is sent to the first I/O port
of the fourth module 4. The fourth module 4 will compare the
electric potential at the first I/O port with a preset value. If
the electric potential at the first I/O port is larger than the
preset value, the fourth module 4 will set the gate of a first
switch at a relative low level through a second I/O port. Once the
two-way control switch is not conducted, the first coil cannot be
electrified. Therefore, the armature 100 cannot be pushed to press
at the locking device 203 to actuate the locking device 203. In
other words, the armature 100 cannot be moved from a first position
as shown in FIG. 5A to a second position as shown in FIG. 5B.
Correspondingly, the locking device 203 cannot be moved from a
first position as shown in FIG. 5A to a second position as shown in
FIG. 5B. Therefore, the movable terminal 201 1 cannot be driven by
the supporting frame 204 to contact with the fixed terminal 202
that the movable terminal 201 cannot be moved from a first position
as shown in FIG. 5A to a second position as shown in FIG. 5B. The
electrical connection between the power supply and the load is cut
off once the movable terminal 201 is moved away from the fixed
terminal 202 under a fault circuit condition. Thus, even though the
trip breaker is reset by the reset button 301, the movable terminal
201 cannot be moved to contact with the fixed terminal 202 to keep
the load from electrically disconnecting with the power supply. In
other words, the load cannot be electrically connected to the power
supply unless the problem of wire misconnection is fixed.
FIG. 6 illustrates the operation of the trip breaker prohibiting
the re-connection between the load and the power supply even though
the trip breaker is reset by the reset button 301, as the wires are
reversely connected. Since the supply of the power of the trip
breaker device is from the load side, the first coil of the trip
breaker cannot be electrified when the wires are reversely
connected. Therefore, the armature 100 cannot be pushed to press at
the locking device 203 to actuate the locking device 203. In other
words, the movable terminal 201 cannot be contacted with the fixed
terminal 202 to electrically connect the load with the power
supply. Even though the trip breaker is reset by the reset button
301, the movable terminal 201 cannot be moved to contact with the
fixed terminal 202 to keep the load from electrically disconnecting
with the power supply
As illustrated above, the present invention can automatically cut
off the power supply of the hot wire and neutral wire to the load
as ground fault circuit interrupter, when the hot wire or neutral
wire is grounded with fault. The two LED indicators indicate that
whether the circuit is electrified and whether the ground fault
circuit interrupter is interrupted or operating. In the present
invention, the power supply and the load cannot be electrically
connected when the wire is misconnected or reversely connected in
an improper manner. The present invention, based on the
programmable integrated module, can automatically cut off the power
supply of the hot wire and neutral wire to the load, can perform
the function of self-check, and can indicates whether the ground
fault circuit interrupter is interrupted.
Referring to FIG. 7 of the drawings, the ground fault circuit
interrupter is generally constructed by seven modules, wherein the
electrical configurations of the programmable integrated module and
the ground fault circuit interrupter are illustrated in FIGS. 8 and
9 respectively.
The first module 1 is a power supply module, wherein the first
module 1 comprises a bridge silicon rectifier stack, a filter
capacity, a stabilivolt circuit. Accordingly, the first module 1 is
adapted to provide and rectify +5 V power supply for the
programmable integrated module. The power supply module, which is
small in size, ensures the efficiency of the power supply in a
stable manner.
The second module 2 is an induction device and a signal rectifying
circuit, wherein the second module 2 comprises two zero-phase
current inductors, which are a sensor coil and a driver coil, and a
capacitor set. One of the current inductors has a coil ratio of
primary and secondary windings being set as 1:1000 while another
current inductor has a coil ratio of primary and secondary windings
being set as 1:200. Each of the zero-phase current inductors
incorporates with the iron core made of ring microcrystalline
material to minimize the tolerance deviation of the angular
measurement.
The third module 3 is a signal amplifying circuit, which comprises
four operational amplifiers by using unipolar +power supply. One of
the operational amplifiers incorporates with an emitter follower to
ensure the impedance matching between the inductor and the
following amplifiers. Another two operational amplifiers are used
for cascade amplification. Accordingly, each of the operational
amplifiers has a gain of 24 dB such that the total gain of the two
operational amplifiers is 48 dB.
The fourth module 4 is a programmable integrated module which
incorporates with a 8-bit programmable integrated module from
Microchip Company, wherein the electrical configuration of the
programmable integrated module is shown in FIG. 8. When the ground
fault circuit interrupter is connected to the power supply, a LED
indicator is electrified to generate an illuminating operation
signal to indicate the operation of the ground fault circuit
interrupter. Therefore, the programmable integrated module will
perform a self-checking operation. During the self-checking
operation, the I/O port of the LED indicator, which is also used as
an indicator for End-of-life indication, and the I/O port of the
reset button 301 are set at a relatively low electrical level. If
the reset button 301 is actuated after the self-checking operation
is completed, the I/O port of the reset button 301 is set at a
relatively high electrical level. The programmable integrated
module sets the I/O port of the control switch at the gate at a
relatively high level. Accordingly, when the control switch is
conducted, the loop of the trip breaker is closed to drive the
movable terminal 201 contacting with the fixed terminal 202 so as
to electrically connect the load with the power supply. Then, the
programmable integrated module will periodically inquire the
inquiring signal from the sensor coil through the third module 3,
wherein the inquiring time of the programmable integrated module is
about 1 ms. Accordingly, the inquiring signal will be compared with
a preset value. When the value of the inquiring signal is larger
than the preset value, the gate of the programmable integrated
module at the I/O port will set the control switch at a high level
such that the control switch is conducted to electrify the second
coil of the trip breaker. Therefore, the movable terminal 201 is
moved away from the fixed terminal 202 to cut off the electrical
connection between the load and the power supply. When the value of
the inquiring signal is smaller than the preset value, the
programmable integrated module will perform the End-of-life
self-checking operation. Once the self-checking operation is
completed, the programmable integrated module will keep determining
the operation current through the sensor coil. If the operation
current does not exceed the preset value, the programmable
integrated module will repeatedly monitor the operation current and
perform the self-checking operation.
The fifth module 5 comprises an automatic self-checking circuitry
to perform the automatic self-checking operation. Regarding to the
UL requirement, the ground fault circuit interrupter requires
checking the fault of the neutral wire connection. A 1 ohm resistor
is electrically connected between the neutral wire and the ground
wire in a series connection, wherein the trip breaker checks
whether there is a fault current between the neutral wire and the
ground wire when the operation current passes through the 1 ohm
resistor. Accordingly, the control switch, having a breakdown
voltage between source and drain above 60V, and has an
on-resistance smaller than 0.1 ohm, is electrically coupled between
the neutral wire and the ground wire in a series connection. Thus,
a resistor is electrically coupled between the source and the
ground wire in a series connection to ensure the series resistance
smaller than 1 ohm between the neutral wire and the ground wire
when the source and drain conducts. The gate of the control switch
is set at a relatively high level at a time interval of one minute
through an I/O portion of the programmable integrated module of the
fourth module 4 to conduct the control switch. An induction current
is inducted at the secondary winding of the sensor coil by
electrically coupling the driver coil with the sensor coil by
electromagnetic force. The induction current is amplified by the
third module 3 and is sent to the fourth module 4. Then, the fourth
module 4 will compare the induction current with a preset
threshold. When the value of the induction current is the same as
the preset threshold, the first to fourth modules 1-4, are
operating normally. The I/O port of the fourth module 4 for
indicating the End-of-life is set at a relatively low level,
wherein the LED indicator will generate a slow-twinkling signal at
a frequency of 10 seconds. When the value of the induction current
is larger than the preset threshold, the I/O port of the fourth
module 4 is set at a relatively low level while the LED indicator
will generate a fast-twinkling signal at a frequency of 1 second.
Meanwhile, the programmable integrated module sets the gate of the
control switch of the second coil of the trip breaker at a high
level to conduct the control switch tube. Once the control switch
is conducted, the trip breaker cuts off the electrical connection
between the power supply and the load. If the control switch or the
trip breaker is malfunctioned, the electrical connection between
the load and the power supply cannot be cut off. However, the LED
indicator will generate the fast-twinkling signal to indicate the
life of the ground fault circuit interrupter is terminated. A
transient voltage suppressor is electrically coupled to the source
and drain of the control switch in a parallel connection, wherein
the transient voltage suppressor, having a 60V breakdown voltage,
is arranged to protect the control switch from being broken down
due to the high electric potential difference-between the neutral
wire and the ground wire.
On the other hand, when the neutral wire and hot wire are
improperly connected, the breakdown voltage of the transient
voltage suppressor 60V is far lower than the voltage between the
neutral wire and hot wire. Therefore, the transient voltage
suppressor is conducted to protect the control switch. At the same
time, a large residual current is produced between the neutral wire
and hot wire. Accordingly, the large residual current is obtained
by the second module 2 to cut off the electrical connection between
the load and the power supply via the fourth module 4 and the sixth
module 6. Unless the electrical connection between the neutral wire
and the hot wire is properly connected, the first coil of the trip
breaker cannot be inducted even though the reset button 301 is
actuated. In other words, the armature 100 will not be driven to
move such that the locking device 203 cannot be actuated to
electrically re-connect the load with the power supply.
The sixth module 6 illustrates the mechanism of the trip breaker,
wherein the sixth module 6 comprises the control switch, the trip
breaker, the movable terminal 201, and the fixed terminal 202. The
control switch is operatively controlled by the fourth module 4.
When the fault current is larger than the preset threshold, the
switch control is conducted to electrify the second coil of the
trip breaker. Therefore, the armature 100 is driven to move the
locking device 203 so as to move the movable terminal 201 away from
the fixed terminal 202 via the resilient spring force. In other
words, the electrical connection between the load and the power
supply is cut off.
The seventh module 7 illustrates the accessories of the trip
breaker and their functions, wherein the seventh module 7 comprises
a reset circuitry with the reset button 301 and a test circuitry
with the test button 302. Accordingly, when the reset button 301 is
actuated by a pressing force, a reset signal is sent to the fourth
module 4 so as to set the I/O port of the fourth module 4 at a
relatively high level. Accordingly, the fourth module 4 is arranged
to monitor the status of the reset button 301 when the reset button
301 is actuated. After the fourth module 4 checks the actuation of
the reset button 301, the control switch of the sixth module 6 is
triggered at a relatively high electric potential to induct the
first coil of the trip breaker. The armature 100 is actuated by the
first coil through the electromagnetic force to actuate the locking
device 203. Once the locking device 203 is actuated, the movable
terminal 201 is moved away from the fixed terminal 202 by the
resilient spring force so as to cut off the electrical connection
between the load and the power supply. Accordingly, the circuitry
of the test button 302 is electrically coupled with the hot wire
and the neutral wire of the load, wherein a 22K resistor is
electrically coupled with the circuitry of the test button 302 in
series connection. When the primary winding of the sensor coil of
the second module 2 produces a 6 mA current, the current is
amplified through the third module 3 and is compared through the
fourth module 4. Then, a trigger signal is produced to the seventh
module 7 to conduct the switch control. Once the switch control is
conducted to electrify the second coil of the trip breaker, the
armature 100 is actuated to actuate the locking device 203. Once
the locking device 203 is actuated, the movable terminal 201 is
moved away from the fixed terminal 202 by the resilient spring
force so as to cut off the electrical connection between the load
and the power supply.
As illustrated above, the present invention can automatically cut
off the power supply of the hot wire and neutral wire to the load
as ground fault circuit interrupter when the hot wire or neutral
wire is grounded with fault. The two LED indicators indicate that
whether the circuitry of the ground fault circuit interrupter is
electrified and whether the ground fault circuit interrupter is
interrupted or operating. In the present invention, the power
supply and the load cannot be re-connected when the wire is
misconnected and improperly connected.
The present invention, bases on the programmable integrated module,
can automatically cut off the power supply of the hot wire and
neutral wire to the load, has the function of self-check, and can
indicates whether the ground fault circuit interrupter is
interrupted.
* * * * *